Gayana (Jan 2003)
ACTIVIDAD DE LA LACTICO DEHIDROGENASA (LDH) EN EMERITA ANALOGA (STIMPSON 1857) CRUSTACEA, HIPPIDAE LACTIC DEHYDROGENASE ACTIVITY (LDH) IN EMERITA ANALOGA (STIMPSON 1857) CRUSTACEA, HIPPIDAE
Abstract
Emerita analoga (Stimpson 1857) habita en la zona infralitoral de playas arenosas, desarrollando intensa movilidad en la zona de barrido y embate de las olas. Su habilidad motriz, reflejada en una constante actividad muscular explosiva, sugiere una alta actividad glicolítica (fermentativa) complementaria a la fosforilación oxidativa. En este trabajo se determinó la actividad específica aparente de la láctico dehidrogenasa (LDH EC 1.1.1.27) de E. analoga como indicador de hipoxia funcional. Además, se estudió el efecto del peso y del pH sobre la actividad LDH, así como en los valores aparentes de sus parámetros cinéticos (Vmax y Km). Los resultados indican que los organismos grandes ( a 1,5) y pequeños (Emerita analoga (Stimpson 1857) inhabitant sandy beaches, it develops intense activity in swatch and fetch embattle zone of the waves. Its motility reflected by a constant and burst muscular activity, suggests a high glycolitic (fermentative) activity, complementary to the oxidative phosphorilation. In this study, the apparent specific activity of the enzyme lactic dehydrogenase (LDH, EC 1.1.1.27) of E. Analoga was tested, as indicator of functional hypoxia. In addition, the effect of weight and pH on LDH activity was studied, and also the apparent values of its kinetic parameters (Vmax y Km). Our results indicated that apparent specific LDH activity in bigger (1,5 mm) and smaller (<1,5 mm in length) organisms of E. analoga, correspond to a positive allometric pattern (p = 0,0108). The optimal pH for the apparent LDH activity best activity was 7,8 in smaller animals and 5,5 in bigger ones. The results suggest that metabolic acidosis could be regulated at enzymatic level in small animals, and as a muscular buffer in the bigger ones. For the sizes ranges used, enzyme activity showed a Michaelian-Menten kinetic. Vmax value in larger animals was one order of magnitude higher than smaller ones (1,043 and 0,121 mmol min-1 g wet wt-1, respectively). However, we observed a high affinity constant in small organisms than in bigger ones (0,076 and 0,094 mM, respectively). Finally, the positive slope of the curve activity /weight is consistent with the positive allometry described for the anaerobic metabolism, scarcely present in literature. Our results suggest an important role of the LDH activity on the motility of E. analoga during its ontogenetic development in the infra-littoral zone
